Bird flu is a significant threat with the potential to spark a catastrophic pandemic. We still have an opportunity to avert a humanitarian disaster, but only if we act urgently, precisely, and forcefully. This entails a major collective rethinking of our approach to managing infectious diseases—embracing a “One Health” strategy that emphasizes preventing human infections before they become widespread, rather than merely reacting quickly after cases have become common. As the Canada Research Chair in Viral Pandemics and head of the M.G. DeGroote Institute for Infectious Disease Research at McMaster University, my career has been dedicated to studying past pandemics and devising new prevention methods for the future.
The actions taken now will determine whether the highly pathogenic avian influenza (HPAI) H5N1 outbreak, which already affects birds and mammals globally, will also infect humans. For about five years, we have monitored the worldwide spread of this H5N1 strain since its initial appearance in wild birds. We’ve observed its leap to domestic poultry, prompting the culling of millions of chickens, turkeys, and ducks to control the virus.
International anxiety about this virus’s pandemic potential rose substantially in 2022 after HPAI H5N1 was confirmed to have crossed to mammals like foxes, skunks, ferrets, and seals. These animals are more similar to humans than birds, allowing the virus to better adapt to infect us. By March, it had spread to dairy cattle in Texas, with testing showing 20 per cent of the area’s milk supply had been affected by H5N1 (though still safe for consumption due to pasteurization). Infected cows were found across the country.
Recently, reports surfaced of H5N1 infections in three farm workers in the United States, with two experiencing conjunctivitis (pink eye) and another having respiratory symptoms. Unfortunately, someone in Mexico recently died from an H5N2 infection, closely related to H5N1. There are likely many more cases. Dairy farms could become hazardous virus incubators due to mechanized milking and facility cleaning that disperses airborne droplets, posing a significant threat of human infection.
Human-to-human transmission of this H5N1 virus has yet to be observed, but it is continually adapting to new hosts. The initial animal-to-human infections offer the virus opportunities to learn how to survive in people. Past avian influenza outbreaks have been fatal for over half of those infected, like viruses such as Ebola, not seasonal flu or even COVID-19. The potential for high human mortality makes this influenza a critical issue. There are ways to stop H5N1, but it’s uncertain if they will be implemented.
While the recent outbreak-causing viruses like Zika were hard to prevent, influenza viruses are a familiar pandemic risk and have caused four pandemics from 1918 to 2009. Given our experience with COVID-19, allowing bird flu to spread would represent a major oversight. Some may question the need to prevent a pandemic when we have tools like masks, drugs, and vaccines to control spread and manage illness. However, it is not simple. When COVID-19 appeared, we had no vaccines for coronaviruses, making the development of COVID-19 vaccines a massive task.
For H5N1, we can use similar technologies to those producing seasonal flu vaccines by adapting formulations for its human form. But that cannot happen immediately, and by the time bird flu hits humans, it might be too late. Vaccine production takes time, especially on a global scale, requiring over eight billion doses.
During the 2009 H1N1 swine flu outbreak, the pandemic peaked before a vaccine was available—despite existing global flu vaccine infrastructure. The most affected would be people in remote and Indigenous communities, the poor, the elderly, medically at-risk individuals, young children, and the displaced.
Efforts are starting globally to prevent the virus from entering human populations, with measures like infection controls for farm animals and personal protective equipment for farm workers. Those at high risk of exposure may need vaccinations and medications to prevent full-blown infections, similar to how we provide rabies vaccines to those working closely with wild animals.
Though plans are forming, they will only work if people adopt them. We witnessed significant resistance to masks and vaccines during COVID-19. Combating bird flu will require public support and resources. Prevention strategies should consider the most affected. Farmers, hunters, and others frequently exposed to potentially infected animals will need proper education and information to understand their importance. Approaches should be based on evidence and offer options as much as possible. Mandates should be the last option.
Those whose livelihoods are threatened by biosecurity costs will need support to take actions that could save millions. Achieving this requires new policies and coordinated efforts among agencies handling farm animal, human, and wildlife health. Canada is making promising strides in this direction but cannot stop a bird flu pandemic alone. However, it’s a chance to show international leadership in effective pandemic prevention.
In the United States, it’s vital not to hide infections among farm workers due to immigration status or lack of health insurance. Another major risk after COVID-19 is the politicization of infection prevention, where public pushback, anti-science attitudes, and misinformation could be as deadly as a conflict. Our approach and communication need to be understanding and aware of these issues to avoid further polarization.
Terrorist attacks are seen as intelligence failures in national security. After 9/11, governments heavily invested in improving security at airports and cities, changing travel and public events, yet today we accept rigorous safety measures without question. Preventing pandemics requires a similar mindset, starting with avian flu, where many millions are at risk. We must change our approach from reaction to prevention.